Dynamic allocation of equality engine in Theory (#4890)

This commit updates Theory so that equality engines are allocated dynamically. The plan is to make this configurable based on the theory combination method.

The fundamental changes include:
- Add `d_equalityEngine` (raw) pointer to Theory, which is the "official" equality engine of the theory.
- Standardize methods for initializing Theory. This is now made more explicit in the documentation in theory.h, and includes a method `finishInitStandalone` for users of Theory that don't have an associated TheoryEngine.
- Refactor TheoryEngine::finishInit, including how Theory is initialized to incorporate the new policy.
- Things related to master equality engine are now specific to EqEngineManagerDistributed and hence can be removed from TheoryEngine. This will be further refactored in forthcoming PRs.

Note that the majority of changes are due to changing `d_equalityEngine.` to `d_equalityEngine->` throughout. 

1 files changed, 25 insertions, 16 deletions

diff --git a/src/theory/arith/congruence_manager.cpp b/src/theory/arith/congruence_manager.cpp
index ab3b485a8..a70339c01 100644
--- a/src/theory/arith/congruence_manager.cpp
+++ b/src/theory/arith/congruence_manager.cpp
@@ -42,16 +42,29 @@ ArithCongruenceManager::ArithCongruenceManager(
       d_constraintDatabase(cd),
       d_setupLiteral(setup),
       d_avariables(avars),
-      d_ee(d_notify, c, "theory::arith::ArithCongruenceManager", true)
+      d_ee(nullptr)
 {
-  d_ee.addFunctionKind(kind::NONLINEAR_MULT);
-  d_ee.addFunctionKind(kind::EXPONENTIAL);
-  d_ee.addFunctionKind(kind::SINE);
-  d_ee.addFunctionKind(kind::IAND);
 }
 
 ArithCongruenceManager::~ArithCongruenceManager() {}
 
+bool ArithCongruenceManager::needsEqualityEngine(EeSetupInfo& esi)
+{
+  esi.d_notify = &d_notify;
+  esi.d_name = "theory::arith::ArithCongruenceManager";
+  return true;
+}
+
+void ArithCongruenceManager::finishInit(eq::EqualityEngine* ee)
+{
+  Assert(ee != nullptr);
+  d_ee = ee;
+  d_ee->addFunctionKind(kind::NONLINEAR_MULT);
+  d_ee->addFunctionKind(kind::EXPONENTIAL);
+  d_ee->addFunctionKind(kind::SINE);
+  d_ee->addFunctionKind(kind::IAND);
+}
+
 ArithCongruenceManager::Statistics::Statistics():
   d_watchedVariables("theory::arith::congruence::watchedVariables", 0),
   d_watchedVariableIsZero("theory::arith::congruence::watchedVariableIsZero", 0),
@@ -141,10 +154,6 @@ bool ArithCongruenceManager::canExplain(TNode n) const {
   return d_explanationMap.find(n) != d_explanationMap.end();
 }
 
-void ArithCongruenceManager::setMasterEqualityEngine(eq::EqualityEngine* eq) {
-  d_ee.setMasterEqualityEngine(eq);
-}
-
 Node ArithCongruenceManager::externalToInternal(TNode n) const{
   Assert(canExplain(n));
   ExplainMap::const_iterator iter = d_explanationMap.find(n);
@@ -320,9 +329,9 @@ bool ArithCongruenceManager::propagate(TNode x){
 
 void ArithCongruenceManager::explain(TNode literal, std::vector<TNode>& assumptions) {
   if (literal.getKind() != kind::NOT) {
-    d_ee.explainEquality(literal[0], literal[1], true, assumptions);
+    d_ee->explainEquality(literal[0], literal[1], true, assumptions);
   } else {
-    d_ee.explainEquality(literal[0][0], literal[0][1], false, assumptions);
+    d_ee->explainEquality(literal[0][0], literal[0][1], false, assumptions);
   }
 }
 
@@ -392,9 +401,9 @@ void ArithCongruenceManager::assertionToEqualityEngine(bool isEquality, ArithVar
 
   Trace("arith-ee") << "Assert " << eq << ", pol " << isEquality << ", reason " << reason << std::endl;
   if(isEquality){
-    d_ee.assertEquality(eq, true, reason);
+    d_ee->assertEquality(eq, true, reason);
   }else{
-    d_ee.assertEquality(eq, false, reason);
+    d_ee->assertEquality(eq, false, reason);
   }
 }
 
@@ -417,7 +426,7 @@ void ArithCongruenceManager::equalsConstant(ConstraintCP c){
   d_keepAlive.push_back(reason);
 
   Trace("arith-ee") << "Assert equalsConstant " << eq << ", reason " << reason << std::endl;
-  d_ee.assertEquality(eq, true, reason);
+  d_ee->assertEquality(eq, true, reason);
 }
 
 void ArithCongruenceManager::equalsConstant(ConstraintCP lb, ConstraintCP ub){
@@ -441,11 +450,11 @@ void ArithCongruenceManager::equalsConstant(ConstraintCP lb, ConstraintCP ub){
   d_keepAlive.push_back(reason);
 
   Trace("arith-ee") << "Assert equalsConstant2 " << eq << ", reason " << reason << std::endl;
-  d_ee.assertEquality(eq, true, reason);
+  d_ee->assertEquality(eq, true, reason);
 }
 
 void ArithCongruenceManager::addSharedTerm(Node x){
-  d_ee.addTriggerTerm(x, THEORY_ARITH);
+  d_ee->addTriggerTerm(x, THEORY_ARITH);
 }
 
 }/* CVC4::theory::arith namespace */